O‐GlcNAc levels modulate adipocytokine transcription

Abstract

Increased flux through the hexosamine biosynthetic pathway and the corresponding increase in intracellular glycosylation of proteins via O‐GlcNAc is sufficient to induce insulin resistance (IR) in multiple systems. Previously, our group used shotgun proteomics to identify multiple rodent adipocytokines whose levels are modulated upon the induction of IR by indirectly and directly modulating O‐GlcNAc levels. We have validated the relative levels of several of these adipocytokines using immunoblotting. Since adipocytokines levels are regulated primarily at the level of transcription and O‐GlcNAc alters the function of many transcription factors, we hypothesized that elevated O‐GlcNAc levels on key transcription factors are modulating adipocytokine expression. Here, we show that upon the elevation of O‐GlcNAc levels and the induction of IR in mature 3T3‐F442a adipocytes, the steady‐state transcript levels of multiple adipocytokines, as measured by quantitative RT‐PCR, reflect the modulation observed at the protein level. We have gone on to validate the adipocytokine transcript levels in mouse models of diabetes. Using inguinal fat pads from the severely IR db/db mouse model and the mildly IR diet‐induced mouse model, we have confirmed that the adipocytokines regulated by O‐GlcNAc modulation in cell culture are likewise modulated in the whole animal upon a shift to IR.R01DK075069(LW)